Dehydrochlorination of alkyl chlorides



United States Patent Ofiiice Patented Oct. 24, 1967 3,349,120 DEHYDROCHLORINATION F ALKYL CHLURHDES Philip Lusman, Edinburgh, Scotland, assignor, by Inesne assignments, to British Hydrocarbon Chemicals Limited, 5 is regenerated at intervals with air or oxygen-containing Londtm, England gases to burn oil the carbon. It is an advantage of the N 'l f F 1964 364,323 process of this invention that carbon deposition as a Claim priority, ap licagaggtijgtgt Britain, May 6, 19 proportion of the feed is reduced, and considerably larger 8 amounts of feedstock can therefore be processed per alll'lb. (Cl. 260-565) l 10 unit Weight of catalyst between regenerations.

The present invention relates to the production of In a preferred embodiment of the invention the feedolefines by the dehydrochlorination of alkyl chlorides. stock is first processed over a relatively large bed, and

The conversion of chlorinated parafl ins to olefines by therefore at a low flow rate, of a silica catalyst which dehydrochlorination in the vapor phase over a catalyst has been pre-treated with alkali as described in our is known. With many catalysts skeletal isomerisation takes copending application Ser. No. 293,861 so obtaining place during the dehydrochlorination reaction, forming an incomplete conversion with minimum skeletal isobranched chain olefines, and this is disadvantageous for merisation, and then over a relatively small bed, and instance where it is desired to obtain primarily straight therefore at a high flow rate, of the silica gel catalyst chain olefines, for use in the production of detergent of the present invention. This process allows for the alkylate or plasticiser alcohols. In our copending applicamaximum possible conversion of the chlorinated paraflin tion Ser. No. 293,861 is described the process for the feed with the least amount of skeletal isomerisation. production of olefines which comprises passing a chlo- The olefines produced by the process can be recovered rinated normal paraffin having from 4 to 20 carbon using conventional means. In cases where paraffin chloriatoms in the vapor phase over a silica catalyst which has nation products are fed to the process and an olefinebeen pre-treated with alkali; the alkali pre-treatment of pa'rafiin mixture is produce-d, this mixture can be fed the catalyst prevents or reduces skeletal isomerisation directly (if desired after removal of a very small amount during the dehydrochlorination reaction. of high boiling by-product which is sometimes formed) It has now been discovered that skeletal isomerisation to the process for which the olefine is required. The over an untreated silica gel catalyst can be prevented or alkylation of the olefine to benzene and the conversion reduced by passing the chlorinated paraflin over the of the olefine to alcohols using the OX0 process are catalyst atahigh flow rate. cases where the olefine/paraffin mixture can be directly According to the present invention the process for utilised in this way. the production of olefines comprises passing a chloro- An important application of the process of the present substituted paraifin having from 4 to 20 carbon atoms invention is in the dehydrochlorination of chlorinated in the vapor phase over a silica gel catalyst at a flow paraflins (especially normal paraffins) in the C C rate in the range from 5 to 30 liquid volumes of chlorirange, preferably in the C C range, to produce olenated paraffin per volume of catalyst per hour. finic products suitable for alkylation to aromatic hydro- A particularly suitable starting material is the reaction carbons such as benzene, using conventional alkylation product of the chlorination of a normal parafiin having catalysts, to give detergent alkylate for use in the profrom 4 to 20 carbon atoms, consisting of a mixture of duction of biodegradable sulphonate detergents, for inthe alkyl chloride with unconverted paraffin. As there stance as described in B.P. 950,975. In this case, the is a tendency for skeletal isomerisation to increase and dehydrochlorinated product, including any paraffin not for the proportion of di-, tri-, and polychloro compounds converted in the chlorination step, can be fed directly formed to rise when the paraffin chlorination conversion to the alkylation step where the olefine is combined with is increased, it is preferred that the degree of chlorination benzene and the unconverted paraffin is recovered from of such reaction mixtures should be kept relatively low, the alkylation step and returned to the chlorination. for example below about The process of the present invention is further illus- The flow rate of the chlorinated pa-rafiins in the vapor trated with reference to the following examples. phase over the catalyst is between 5 and 30 and preferably between 8 and 20 liquid volumes of chlorinated Example 1 paraffin per volume of catalyst per hour. A sample of silica gel of the following properties Silica gels of relatively large average pore diameters Surface area "me/gm" 300 are preferred, gels with average pore diameters over about Average pore Volume ml/gm L04 40 generally giving less side reactions, especially less Average pore diameter 139 crac mg.

The dehydrochlorination is suitably carried out at Sodlum content f Percent 0.2 temperatures i h range 200.500" C, f bl 3 was used to dehydrochlonnate a feedstock made by chlo-, 400 C. Atmospheric pressure, or increased or reduced Tinating a C1O"C13 normal Pafafiln fraction to a Chlorine pressures can be used. Diluents, such as lower parafi'lns Content of about P the Conditions d r or inert gases such as nitrogen can be used, the unconsults being summarised in the following table:

TABLE 1 Weight Relative Percent percent Dehydro- Liquid flow cone. of conversion chlorine in chlorination Pressure rate, voL/ branched of chlorofeezl Temp., 0. vol. cat/hr. isomers in paraflin product a. 82 350 Atm. 0. 7 17 99. 5 3.82 350 Atrn. 3. 3 6 99. 5 3.82 350 Atm. 8.2 2 98.7 3. 57 370 Atm. 20. 0 1 95. 3

The branched isomer contents were determined by hydrogenating the products on a palladium oxide/ charcoal catalyst at 20-60 C., which completely converted the olefines to paraflins. The hydrogenated product was then analysed gas chromatographically.

The parafiin/olefines mixture produced at a flow rate of 20 v./ v./ hour was alkylated to benzene using anhydrous hydrofluoric acid as catalyst, the mole ratios of olefine: benzene:HF being 1:10:20. The detergent alkylate fraction of the product had a refractive index (11, of 1.483 indicating the essentially straight chain character of the side chains. The yield of detergent alk'ylate was about 120 parts per part of normal parafiin consumed.

Example 2 A C C normal parafiin feedstock containing 98.6 wt. percent of normal parafiins was chlorinated to give a chlorine content of 4.22 wt. percent. This chlorinated product was passed over a silica gel catalyst as in Ex ample 1 at a rate of 20 liquid volumes per volume of catalyst per hour at a temperature of 370 C. and at atmospheric pressure. In this test 97% of the chlorine content of the feed was eliminated as hydrogen chloride. The total product from the test was used to alkylate benzene, using anhydrous hydrogen fluoride as catalyst, the mole ratios of olefine:benzene:I-IF being 1:10:20. The alkyl benzene product was recovered from the total alkylation products by fractionation under reduced pressure after separation and removal of the catalyst, the alkyl benzene boiling in the range 270 C. to 320 C. at 760 mm. pressure.

The alkyl benzene was sulphonated in the conventional way with oleum, and the sodium salt tested for biodegradability by measuring the disappearance of active agent when incubated with a standard culture and when aerated under standard conditions. The results, compared with those for a sulphonate derived from the same chloro paraffins dehydrochlorinated at a lower space velocity (0.7 v./v./hr.) over the same catalyst, were as follows:

TABLE 2 Space velocity Percent active agent remaining in dehydroafter 22 days chlorination, v./v.//hour Aeration test Incubation test The product made by dehydrochlorination at 20 v./v./hour is clearly much more biodegradable than that madeat the low space velocity.

Example 3 A chlorinated C -C normal paraflin mixture containing 4.2 wt. percent of chlorine was dehydrochlorinated over the silica gel catalyst of Example 1 at a flow rate of 20 volumes liquid feed pervolume of catalyst per hour, the temperature being 370 C. and the pressure atmospheric. The chlorine content of the total liquid product was determined at intervals during the test, and the percentage of the chlorine initially present in the feed which was removed calculated. The results were as follows:

These figures show that considerable amounts of feed can be processed over the catalyst under these conditions before any large decline. in catalyst activity necessitating regeneration by burning oil the carbon takes place.

I claim:

1. In a process for the production of olefins which comprises passing a chloro-substituted paraffin having from 4 to 20 carbon atoms over a silica catalyst at a temperature in the range of from 200 C. to 500 C., the improvement which comprises suppressing skeletal isomerization by contacting the chloro-substituted paraffin with an untreated silica gel catalyst at a flow rate in the range of 5 to 30 liquid volumes of chlorinated parafiin per volume of catalyst per hour.

2. The improvement according to claim 1 wherein the starting material is the reaction product of the chlorination of a normal parafiin.

3. The improvement according to claim 2 wherein the degree of chlorination of the paraflin in the reaction product is below 40 mole percent.

4. The improvement according to claim 1 wherein the flow rate is in the range from 8 to 20 liquid volumes of i chlorinated parafiin per volume of catalyst per hour.

5. The improvement according to claim 1 wherein the catalyst is a silica gel having an average pore diameter.

over about 40 A. units.

6. In a process for the production of olefins which comprises passing a chloro-substituted paraffin having. from 4 to 20 carbon atoms over a silica catalyst at a temperature in the range of from 200 C. to 500 C., the improvement which comprises suppressing skeletal isomerization by partially dehydrochlorinating the chloro-substituted paraflin by first contacting said parafiin with a silica catalyst at a flow rate below 5 liquid volumes of chlorinated paraffin per volume of catalyst per hour and.

thereafter contacting said paraflin with a silica catalyst at a flow rate in the range of 5 to 30 liquid volumes of chlorinated parafiin per volume of catalyst per hour.

7. The improvement according to claim 6 wherein the silica catalyst with which the chloro-substituted paraffin is contacted at a fiow rate below 5 liquid volumes of chlorinated paraflin per volume of catalyst per hour has been pre-tested with alkali.

8. In a process for the productionof alkylbenzene sulphonate detergent which comprises chlorinating a paraflin feedstock to produce chloro-parafiins, dehydrochlorinating the chloro-parafiins to produceolefins, alkylating benzene with the olefins so produced in. the presenceof an alkylation catalyst and sulphonating the resulting alkylate, the improvement which comprises suppressing skeletal isomerization by using a paraffin feedstock in the range C -C which contains at least normal paraflins and dehydrochlorinating the chloro-parafiins to olefins by passing the chloro-parafiins over a silica gel catalyst at a fiow rate in the range of 5 to 30 liquid volumes of chlorinated paraflin per volume of catalyst per hour.

References Cited UNITED STATES PATENTS 1,995,827 3/1935 Thomas 260671 2,597,910 5/1952 Thaw et a1. 260677 2,708,210 5/1955 Sias 260-677 2,920,122 6/1960 Milton et al 260-677 3,169,987 2/1965 Bloch 260671 X DELBERT E. GANTZ, Primary Examiner.

C. R. DAVIS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,349,120 October 24, 1967 Philip Lusman (SEAL) Attest:

Edward M. Fletcher, Jr. EDWARD J. BRENNER lttesting Officer Commissioner of Patents 

1. IN A PROCESS FOR THE PRODUCTION OF OLEFINS WHICH COMPRISES PASSING A CHLORO-SUBSTITUTED PARAFFIN HAVING FROM 4 TO 20 CARBON ATOMS OVER A SILICA CATALYST AT A TEMPERATURE IN THE RANGE OF FROM 200*C. TO 500*C., THE IMPROVEMENT WHICH COMPRISES SUPPRESSING SKELETAL ISOMERIZATION BY CONTACTING THE CHLORO-SUBSTITUTED PARAFFIN WITH AN UNTREATED SILICA GEL CATALYST AT A FLOW RATE IN THE RANGE OF 5 TO 30 LIQUID VOLUMES OF CHLORINATED PARAFFIN PER VOLUME OF CATALYST PER HOUR.
 8. IN A PROCESS FOR THE PRODUCTION OF ALKYLBENZENE SULPHONATE DETERGENT WHICH COMPRISES CHLORINATING A PARAFFIN FEEDSTOCK TO PRODUCE CHLORO-PARAFFFINS, DEHYDROCHLORINATING THE CHLORO-PARAFFINS TO PRODUCE OLEFINS, ALKYLATING BENZENE WITH THE OLEFINS SO PRODUCED IN THE PRESENCE OF AN ALKYLATION CATALYST AND SULPHONATING THE RESULTING ALKYLATE, THE IMPROVEMENT WHICH COMPRISES SUPPRESSING SKELETAL ISOMERIZATION BY USING A PARAFFIN FEEDSTOCK IN THE RANGE C10-C16 WHICH CONTAINS AT LEAST 95% NORMAL PARAFFINS AND DEHYDROCHLORINATING THE CHLORO-PARAFFINS TO OLEFINS BY PASSING THE CHLORO-PARAFFINS OVER A SILICA GEL CATALYST AT A FLOW RATE IN THE RANGE OF 5 TO 30 LIQUID VOLUMES OF CHLORINATED PARAFFIN PER VOLUME OF CATALYST PER HOUR. 